Herbal viagras, contrary to what the name suggests, do not normally contain sildenafil citrate. However, sildenafil and chemicals similar to sildenafil have been found as adulterants in many supplements which are sold as herbal viagra or "natural" sexual enhancement products.    The United States Food and Drug Administration has warned consumers that any sexual enhancement product that claims to work as well as prescription products is likely to contain such a contaminant.  Scientists estimated that >60% of the consumed sildenafil in the Netherlands is from illegal sources such as adulterated dietary supplements. 
My life came to a virtual halt when doctor said that I have erectile dysfunction which is a consequence of my heart disease. He then prescribed generic viagra and also gave an option for taking the generic version of Viagra. I have taken both brand and generic version. I must say that the generic version is as effective as the brand and its quiet light on pocket so you can opt for pleasure without spending more.
The research surrounding L-citrulline is not conclusive enough to prove that watermelon should be your go-to treatment method for managing symptoms of ED.
Dr. Roxanne Dryden-Edwards is an adult, child, and adolescent psychiatrist. She is a former Chair of the Committee on Developmental Disabilities for the American Psychiatric Association, Assistant Professor of Psychiatry at Johns Hopkins Hospital in Baltimore, Maryland, and Medical Director of the National Center for Children and Families in Bethesda, Maryland.